In one proposed hybrid vehicle having an engine and a motor, a threshold value of the vehicle speed is set based on the temperature of a battery which supplies electric power to the motor and the output value of the battery actually outputting electric power. The threshold value represents a boundary of a region to prohibit operation stop of the engine (see, for example, Patent Document 1). This vehicle is intended for protecting the battery by setting the threshold value of the vehicle speed smaller for the high temperature of the battery while setting the threshold value of the vehicle speed greater for the large actual output from the battery, and by prohibiting the operation stop of the engine when the vehicle speed is greater than the threshold value.    Patent Document 1: Japanese Patent Laid-Open No. 2006-170128